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3 years ago

There are 2.2 pounds in a kilogram. if a boys mass is 40kg, what is his height in pounds?

2 answers:

4 0

There are NOT 2.2 pounds in a kilogram.
Any teacher who makes such a statement is misleading you, and
putting things into your head that will be tough to get rid of later.

2.2 pounds is the approximate WEIGHT of 1 kilogram of MASS
on Earth. The SAME KILOGRAM of mass weighs about 5.8 ounces
on the Moon, and about 11.8 ounces on Mars.

If a boy's mass is 40 kg, then he weighs about 29.2 pounds on Mars,
about 14.7 pounds on the Moon, and about 89 pounds on Earth.

"Height" doesn't belong anywhere in this question.

sasho [114]3 years ago

3 0

The simplest way to do this is to set up equivalent fractions, like this-

$\frac{1}{2.2}$ = $\frac{40}{x}$

Solve for x by using cross multiplication.

40*2.2= 88
1*x=88
x=88

Therefore, the boy weighs 88lbs.

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3 years ago

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A particle with charge Q and mass M has instantaneous speed uy when it is at a position where the electric potential is V. At a

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Answer:

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3 years ago

All waves on the electromagnetic spectrum travel at the same speed in a vacuum. The speed of these waves in a vacuum is 3x10 8 m

Alexandra [31]

As you said, the speed is constant in a vacuum, so the speed does not change, The frequency, on the other hand, decreases by half. The wavelength, λ (lambda), the frequency, v, and the speed of light, c, are related by the equation λν = c. We can see that frequency and wavelength are inversely proportional, so an increase in wavelength has a corresponding decrease in frequency.

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3 years ago

Two sources emit beams of light of wavelength 550 nm. The light from source A has an intensity of 10 μW/m2, and the light from s

alexira [117]

Answer:

A) Beam B carries twice as many photons per second as beam A.

Explanation:

If we have two waves with the same wavelength, then their intensity is proportional to their power, or the energy per unit time.

We also know that the amount of photon present in an electromagnetic beam is proportional to the energy of the beam, hence the amount of beam per second is proportional to the power.

With these two facts, we can say that the intensity is a measure of the amount of photon per second in an electromagnetic beam. So we can say that beam B carries twice as more power than beam A, or Beam B carries twice as many photons per second as beam A.

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3 years ago

Aluminum rivets used in airplane construction are made slightly larger than the rivet holes and cooled by "dry ice" (solid CO2)

poizon [28]

Answer:

$\rm 4.554\ m m.$

Explanation:

Given:

Initial temperature, $\rm T_i=23.0\ ^\circ C=23 + 273.15 = 296.15\ K.$
Final temperature, $\rm T_f = -78.0\ ^\circ C = -78+273.15=195.15\ K.$
Diameter of the hole, $\rm d = 4.500\ m = 4.500\times 10^{-3}\ m.$
Expansion coefficient of the Aluminum, $\rm \alpha = 2.4\times 10^{-5}\ K^{-1}.$

Let the diameter of the rivet at $\rm T_i=23.0\ ^\circ C$ be $\rm d_o$ , such that,

$\rm d_o=d+\Delta d$

$\rm \Delta d$ is the elongation in the diameter of the rivet.

We know, The change in the diameter of the rivet is related with the change in temperature as:

$\rm \dfrac{\Delta d}{d_o}=\alpha \Delta T.$

where, $\rm \Delta T$ is the change in temperature = $\rm T_f-T_i=-195.15-296.15=-491.30\ K.$

Also, $\rm \Delta d=d_o-d.$

Using these values,

$\rm \dfrac{d_o-d}{d_o}=\alpha \Delta T\\1-\dfrac{d}{d_o}=\alpha \Delta T\\\dfrac{d}{d_o}=1+\alpha \Delta T\\\Rightarrow d_o = \dfrac{d}{1+\alpha \Delta T}\\=\dfrac{4.500\times 10^{-3}}{1+2.4\times10^{-5}\times (-491.30)}\\=4.554\times 10^{-3}\ m.\\=4.554\ m m.$

It is the required diameter of the rivet at $-78.0\ ^\circ C$ .

4 0

3 years ago